Coalescence judgment criteria for the interaction between two close surface cracks by WES2805 and its safety margin for brittle fracture assessment

Tomoya Kawabata; Shuji Aihara; Yukito Hagihara; Tomoya Kawabata; Shuji Aihara; Yukito Hagihara

doi:10.3934/matersci.2016.4.1665

AIMS Materials Science

2016, Volume 3, Issue 4: 1665-1682. doi: 10.3934/matersci.2016.4.1665

Previous Article Next Article

Research article Special Issues

Coalescence judgment criteria for the interaction between two close surface cracks by WES2805 and its safety margin for brittle fracture assessment

1.
Department of Systems Innovation, The University of Tokyo, Tokyo 113-8656, Japan
2.
Formerly Sophia University, Japan

Received: 25 August 2016 Accepted: 18 November 2016 Published: 28 November 2016

It is important to consider the interaction between multiple cracks in evaluating the reliability of a structure. In this study, the stress intensity factor (K value) is evaluated using the finite element method for interacting surface cracks. Although there are an infinite number of possible conditions of the locations and sizes of two close cracks, the cracks shall be located parallel to each other and have the same dimensions for simplification in this study. The K values on the crack front are calculated under various aspect ratios and relative locations. When there is a strong interaction (ΔK_max ≥ 10%), fracture analysis is generally performed after the coalescence of the two cracks by the FFS standard. As a result of the investigation of the critical condition of the positional parameters for coalescence, judgement criteria were introduced in WES2805 with some simplification. It was revealed that the coalescence process in WES2805 provides a safety margin.
- stress intensity factor; finite element method; interaction; aspect ratio; safety margin
Citation: Tomoya Kawabata, Shuji Aihara, Yukito Hagihara. Coalescence judgment criteria for the interaction between two close surface cracks by WES2805 and its safety margin for brittle fracture assessment[J]. AIMS Materials Science, 2016, 3(4): 1665-1682. doi: 10.3934/matersci.2016.4.1665

Related Papers:

Abstract

It is important to consider the interaction between multiple cracks in evaluating the reliability of a structure. In this study, the stress intensity factor (K value) is evaluated using the finite element method for interacting surface cracks. Although there are an infinite number of possible conditions of the locations and sizes of two close cracks, the cracks shall be located parallel to each other and have the same dimensions for simplification in this study. The K values on the crack front are calculated under various aspect ratios and relative locations. When there is a strong interaction (ΔK_max ≥ 10%), fracture analysis is generally performed after the coalescence of the two cracks by the FFS standard. As a result of the investigation of the critical condition of the positional parameters for coalescence, judgement criteria were introduced in WES2805 with some simplification. It was revealed that the coalescence process in WES2805 provides a safety margin.

References

[1]	Boiler & Pressure Vessel Code, Section XI (2015) American Society of Mechanical Engineers.
[2]	Codes for Nuclear Power Generation Facilities—Rules on Fitness-for-Service for Nuclear Power Plants (2002) The Japan Society of Mechanical Engineers.
[3]	The Japan Welding Engineering Society (2011) WES2805 (Method of Assessment for Flaws in Fusion Welded Joints with respect to Brittle Fracture and Fatigue Crack Growth).
[4]	BS7910 Guide to methods for assessing the acceptability of flaws in metallic structures. (2013) British Standards.
[5]	Hagihara Y (2004) Review of Fitness-For-Service Codes and Standards. J Jpn Weld Soc 73: 436–441. doi: 10.2207/qjjws1943.73.436
[6]	Hasegawa K, Miyazaki K (2007) Alignment and Combination Rules on Multiple Flaws in Fitness-for-Service Procedures. Key Eng Mater 345–346: 411–416.
[7]	Ishida M (1969) Stress Intensity Factors in Panels with Cracks in the Same Straight Line. T Jpn Soc Mech Eng 35: 1815–1822. doi: 10.1299/kikai1938.35.1815
[8]	Lam KY, Phua SP (1991) Multiple Crack Interaction and Its Effect on Stress Intensity Factor. Eng Fract Mech 40: 585–592. doi: 10.1016/0013-7944(91)90152-Q
[9]	Rubinstein AA (1985) Macrocrack Interaction with Semi-infinite Microcrack Array. Int J Fract 27: 113–119.
[10]	Yokobori T (1971) Interaction between Overlapping Parallel Elastic Cracks. J Jpn Soc Strength Fract Mater 6: 39–50.
[11]	Kamaya M (2000) A Crack Growth Evaluation Method Considering Interaction between Multiple Cracks. T Jpn Soc Mech Eng A 66: 1491–1497. doi: 10.1299/kikaia.66.1491
[12]	Murakami Y, Nishitani H (1981) Stress Intensity Factors by interacting of two semi-elliptical surface cracks. T Jpn Soc Mech Eng 47: 295–303. doi: 10.1299/kikaia.47.295
[13]	Murakami Y, Nemat-Nasser S (1983) Growth and Stability of Interacting Surface Flaws of Arbitrary Shape. Eng Fract Mech 17: 193–210. doi: 10.1016/0013-7944(83)90027-9
[14]	Miyata H, Kusumoto A (1979) Stress Intensity Factors of three dimensional Cracks. T Jpn Soc Mech Eng A 45: 252–259. doi: 10.1299/kikaia.45.252
[15]	Yoshimura S (1995) New Probabilistic Fracture Mechanics Approach with Neural Network-based Crack Modeling: Its Application to Multiple Cracks Problem. ASME PVP 304: 437–442.
[16]	Noda N (1998) Analysis of Variation of Stress Intensity Factor along Crack Front of Interacting Semmi-Elliptical Surface Cracks. T Jpn Soc Mech Eng A 64: 879–884. doi: 10.1299/kikaia.64.879
[17]	Meessenm O (2000) Applications of Cracked Bricks in Fracture Mechanics : Redustion of ASME Conservatism and Suggestion for ASME Section XI Code Changes. ASME PVP 407: 221–228.
[18]	Miyoshi T (1984) Study on Stress Intensity Factors of Closely Located or Partly Overlapped Twin Surface Cracks. T Jpn Soc Mech Eng A 50: 477–482. doi: 10.1299/kikaia.50.477
[19]	Kamaya M, Kitamura T (2002) Stress Intensity Factors of Interacting Parallel Surface Cracks. T Jpn Soc Mech Eng A 68: 1112–1119. doi: 10.1299/kikaia.68.1112
[20]	Kawabata T, Konda N, Hagihara Y (2006) Stress Intensity Factors of Two Close Surface Cracks and Their Interaction Criterion. T Jpn Soc Mech Eng A 72: 1310–1317.
[21]	Hagihara Y (2008) Main Points of Revised WES 2805-2007. J Jpn Weld Soc 77: 685–688. doi: 10.2207/jjws.77.685
[22]	ABAQUS/Analysis User’s Manual Version 6.5 (2000) Hibbitt, Karlsson & Sorensen, Inc.
[23]	Itoh YZ, Murakami T, Kashiwaya H (1988) Approximate formulae for estimating the j-integral of a circumferentially cracked round bar under tension or torsion. Eng Fract Mech 31: 967–975.
[24]	Newman JC, Raju Jr IS (1981) An Empirical Stress-Intensity Factor Equation for Surface Crack. Eng Fract Mech 15: 185–192. doi: 10.1016/0013-7944(81)90116-8
[25]	Noda NA (2001) Variation of the Stress Intensity Factor along the Crack Front of Interacting Semi-elliptical Surface Cracks. Arch Appl Mech 71: 43–52. doi: 10.1007/s004190000113
[26]	Pommier S (1999) An Empirical Stress Intensity Factor set of Equations for a Semi-Elliptical Crack in a Semi-Infinite Body Subjected to a Polynomial Stress Distribution. Int J Fatigue 21: 243–251. doi: 10.1016/S0142-1123(98)00074-7
[27]	Ishida M (1984) Tension and Bending of Finite Thickness Plates with a Semi-elliptical Surface Crack. Int J Fract 26: 157–188. doi: 10.1007/BF01140626

Reader Comments

Your name:*

Email:*
© 2016 the Author(s), licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0)